Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G25/00—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents
  • C10G25/12—Recovery of used adsorbent
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G25/00—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents
  • C10G25/02—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents with ion-exchange material
  • C10G25/03—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents with ion-exchange material with crystalline alumino-silicates, e.g. molecular sieves

Definitions

• This invention relates to a cyclic process for the separation of n-paraffins from mixtures thereof together with non-straight chain hydrocarbons, e.g. cycloparaffins, isoparaffins and aromatics, using a bed of 5A molecular sieve.
• non-straight chain hydrocarbons e.g. cycloparaffins, isoparaffins and aromatics
• n-paraffins are able to enter the pores of the sieve and when a feed containing n-paraffins in admixture with non-straight chain hydrocarbons, e.g. branched chain or cycloparaffins, is passed through the bed of the sieve, the branched chain and cycloparaffins come out in the effluent and the n-paraffins are adsorbed. The n-paraffins are subsequently removed in a separate stage called a desorption stage.
• n-paraffins which are the effluent from the desorption stage
• non-straight chain hydrocarbons denormal product
• the desired product is usually the n-paraffins
• the feed is a gasoline
• the desired product is usually the relatively high octane non-straight chain hydrocarbons.
• Each process is usually operated to maximise the yield of the desired product.
• n-paraffin product is in the production of protein by the cultivation of micro-organisms.
• the n-paraffin product is required to be of very high purity, typically at least 98% wt or even higher.
• a cyclic vapour phase process for separating n-paraffins boiling in the gasoline, kerosine or gas oil ranges from a feed mixture thereof with non-straight chain hydrocarbons, by means of a bed of a 5A molecular sieve comprises:
• the feed is stopped to the adsorption stage when at least 50% of the breakthrough volume (as hereinafter defined) has been passed and a mixture richer in n-paraffins than the feed is passed through the bed.
• the front which moves through the bed in the adsorption stage is not sharp and the content of n-paraffins in the effluent increases from typically 0.2% to the same value as the feed over a period of several seconds.
• the breakthrough point is considered to be the mid point of the period in which the composition of the effluent increases from the level prevailing during the greater part of the adsorption stage, i.e., about 0.2%, to that of the feed.
• the breakthrough volume is the volume of feed passed into the bed from the start of the adsorption stage to the breakthrough point.
• the desorption can be effected by pressure reduction as described in U.K. Pat. Nos. 1,026,116 and 1,110,494.
• a purge stage is interposed between the adsorption and desorption stages to remove surface adsorbed and interstitial material.
• the purge stage can be effected by pressure reduction, for example, as disclosed in the above mentioned UK Patents.
• the feed can be fresh material, e.g., direct from a hydrofiner or distillation unit, or can be an admixture of fresh material with streams from other parts of the process, e.g., purge effluent or partly denormalised material obtained as an effluent in the adsorption stage after breakthrough.
• the mixture richer in n-paraffins than the feed is preferably effluent obtained from the purge stage or n-paraffin product obtained as effluent from the desorption stage.
• Preferably 50-150% of the breakthrough volume of feed is passed through the bed, more preferably 90-110%, in the adsorption stage before introduction of the mixture richer in n-paraffins than the feed.
• the feed and the n-paraffin richer mixture are passed at constant rates in the gas phase so the volumes passed into the bed are proportional to the durations for which they are passed.
• the molecular sieve is conventionally held in a vessel called an adsorber.
• the purpose of passing the n-paraffin richer mixture is to increase the n-paraffin content of the void spaces in the adsorber and the macroporous structure of the sieve.
• n-paraffin richer mixture e.g. n-paraffin product
• n-paraffin richer mixture When the n-paraffin richer mixture is effluent from a purge stage it is preferred to pass the entire effluent collected from the purge stage as the n-paraffin richer mixture rather than to blend part with the feed mixture.
• the mixture richer in n-paraffins than the feed contains at least 10% by wt. more n-paraffins than the feed, more preferably at least 20% more.
• a purge effluent contains from 30-80% by wt. of n-paraffins.
• n-Paraffin product typically contains at least 95% wt. n-paraffins, often as least 98% wt. n-paraffins.
• the adsorption stage of one cycle follows immediately after the desorption stage of a preceding cycle. Because desorption is effected by pressure reduction, the pressure in the bed at the start of the adsorption stage is therefore very low and a first part of the adsorption stage is preferably carried out as a pressurising up step by passing the feed into the bed but keeping the outlet valve(s) closed.
• Preferred operating temperatures for different range feedstocks are 325°-375° C for gasoline, 350°-400° C for kerosine, and 380°-420° C for gas oil.
• Preferred adsorption pressures also vary with the feedstock, being 5-500 psia for gasoline and 5-50 psia for kerosine and gas oil.
• the preferred intermediate purge pressure also depends upon the actual boiling range of the feedstock. For example, when treating a gasoline fraction of average carbon number about C 7 boiling in the range C 4 --180° C, a purge pressure range of 2-50 psia is preferred, while 5-150 torr is preferred for kerosine range fractions of average carbon number about C 11 boiling between 150°-250° C, and for gas oil fractions.
• the preferred desorption pressure varies according to the feedstock boiling range, being in the range 10-300 torr for gasoline and 0.1-20 torr for kerosine and gas oil fractions.
• the pressure reduction in the third stage, desorption, is preferably achieved by direct condensation with recycled n-paraffin product.
• the pressure reduction in the third stage is preferably achieved by means of an ejector, for example as described in our copending British application No. 35614/73.
• the durations of the three stages may be such that the desorption plus purge duration is a simple multiple of the adsorption duration. Alternatively, and preferably, however, the durations of the adsorption and desorption are whole-number multiples of the purge.
• the purge duration should not exceed three minutes, one or two minutes being preferred.
• the adsorption and desorption periods may be, respectively, 1-5, preferably 1-2 minutes, and 2-10, preferably 3-8 minutes.
• the process is preferably operated using a number of fixed beds of sieve so that at any given time, one or more beds are adsorbing, purging and desorbing.
• the ratio of the number of beds respectively, adsorbing, purging and desorbing at any given moment is preferably the same as the ratio of the durations of the adsorption, purge and desorption stage.
• This ratio may be 1:1:n where n is an integer between 1 and 6, 1:1:3 being preferred.
• a ratio of 1:1:3 is required.
• a further additional bed may also be provided to permit periodic regeneration, e.g., by burning off, to remove carbonaceous deposits without interrupting the adsorption-purge-desorption cycle.
• the feed rate to the adsorption stage is preferably 0.5-2.5 v/v/hour, particularly 1.0-2.0 v/v/hour.
• the proportions of the adsorption stage devoted to feed mixture and purge effluent will preferably be proportional to the amount of feed mixture and purge effluent.
• n-paraffin richer mixture is n-paraffin product
• preferably 5-15 seconds of the adsorption stage is devoted to passing the n-paraffin product into the bed.
• the fresh feed was a hydrofined gas oil boiling in the range 240°-330° C, containing 20 percent weight of n-paraffin and a sulphur content of 120 ppm.
• the sieve was a 5A molecular sieve, consisting of 4-8 mesh beads.
• the adsorber was 5 feet long and 4 inches in diameter and contained 8.3 kg of sieve.
• the purge effluent was the same as the previous cycle. 125 ml of 45 percent weight n-paraffins were obtained.
• the desorption effluent contained 98 percent weight n-paraffins and was obtained at a rate of 0.80 percent sieve weight/cycle.
• the desorption effluent contained 98.5 percent weight n-paraffins and was obtained at a rate of 0.8 percent sieve weight/cycle.
• n-Paraffin product passed at the end of the adsorption stage.
• the desorption effluent contained 99.0 percent weight n-paraffins and was obtained at a rate of 0.8 percent sieve weight/cycle.

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10038932

Family Applications (1)

Country Status (9)

Cited By (5)

Citations (6)

Family Cites Families (2)

• 1975
  • 1975-04-08 GB GB14313/75A patent/GB1512401A/en not_active Expired
• 1976
  • 1976-03-22 US US05/668,843 patent/US4059505A/en not_active Expired - Lifetime
  • 1976-03-26 IT IT21649/76A patent/IT1058592B/it active
  • 1976-03-31 NL NL7603336A patent/NL7603336A/xx not_active Application Discontinuation
  • 1976-04-01 DE DE19762613974 patent/DE2613974A1/de not_active Withdrawn
  • 1976-04-02 FR FR7609634A patent/FR2307031A1/fr not_active Withdrawn
  • 1976-04-06 JP JP51037867A patent/JPS51123201A/ja active Pending
  • 1976-04-07 SU SU762342412A patent/SU650496A3/ru active
  • 1976-04-08 BE BE165968A patent/BE840532A/xx unknown

Patent Citations (6)

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